Efficiency and ecological safety evaluation of Bjerkandera adusta DH0817 for sulfadiazine-contaminated soil remediation at low temperatures

The bioremediation of antibiotic-contaminated soil in cold regions is hindered by low degradation efficiency and insufficient ecological safety evaluation. This study developed a solid-state fermentation agent using the psychrotolerant white-rot fungus Bjerkandera adusta DH0817 cultured on rice straw and bran, and evaluated its efficacy in sulfadiazine (SDZ)-contaminated soil at 10°C. An application of the agent at 5% (w/w) achieved 73.9% SDZ removal within 30 days. Integrating high-throughput sequencing, functional prediction, and RT-qPCR analyses, this study showed that the introduction of DH0817 significantly accelerated the degradation of SDZ. Furthermore, it was associated with a reduction in both the abundance and diversity of soil bacteria and fungi. Notable alterations in community structure were observed, characterized by decreased abundances of SDZ-tolerant genera such as Pseudaminobacter and TM7a , alongside significant increases in genera including Acinetobacter , Paenarthrobacter , and Penicillium . The predictive results indicated that the application of strain DH0817 could yield beneficial effects on the soil microbial function. Additionally, the introduction of this strain resulted in a decrease in the copy numbers of sulfonamide resistance genes (SA-ARGs), Multidrug resistance genes (MD-ARGs), and Mobile genetic elements (MGEs), while concurrently increasing Aminoglycoside resistance genes (AM-ARGs) and Macrolide-lincosamide-streptogramin B resistance genes (MLSB-ARGs). This phenomenon may potentially heighten public health. This study provides an effective microbial agent for the bioremediation of antibiotic-contaminated soils in cold regions, emphasizing the necessity of assessing soil microbial communities and ARGs throughout the remediation process. Furthermore, it establishes a theoretical foundation for the ecological risk evaluation of environmental microbial remediation technologies.